Tire

ABSTRACT

A tire having a strip layer between breaker and ply using a rubber composition for a strip layer between breaker and ply capable of improving tensile strength at break and elongation at break, capable of also lessening the lowering rate of fracture property after thermal aging, and also being excellent in separation resistance property is provided. A tire having a strip layer between breaker and ply using a rubber composition for a strip layer between breaker and ply comprising (A) 2.0 to 3.9 parts by mass of sulfur, (B) 0.5 to 4 parts by mass of a cresol resin, a modified cresol resin, resorcinol or a modified resorcinol condensate and (C) 0.3 to 3 parts by mass of a partial condensate of hexamethylolmelaminepentamethylether or a partial condensate of hexamethoxymethylolmelamine, based on 100 parts by mass of a diene rubber component, wherein the thickness of the strip layer between breaker and ply is 0.3 to 3.9 mm.

This U.S. patent application claims benefits of Japan Patent ApplicationNo. 2008-199897 filed Aug. 1, 2008.

BACKGROUND OF THE INVENTION

The present invention relates to a tire having a strip layer betweenbreaker and ply using a rubber composition for a strip layer betweenbreaker and ply.

Fracture and separation from fine cracks in rubber between breaker andply is occasionally generated in a radial tire for heavy duty whenrequisites of throughway running and high temperature area areduplicated.

The origination of the fine cracks is occasionally foreign articles inNR or during process and occasionally minerals in an antioxidant or zincoxide badly dispersed.

It is effective for the problem to physically paste a strip rubberbetween breaker and ply to mitigate the concentration of strain, andmethods of extending breaker cushion and additionally pasting the samecompounding are generally carried out.

However, although a cushion rubber has low heat build-up property,reinforcing property and tensile strength at break is not adequate.Accordingly, a rubber having the same compounding as a breaker toppingrubber by which adequate effect in reinforcing property and tensilestrength at break is obtained is used as a strip rubber.

By the way, although a rubber composition used as for breaker topping isdisclosed in the patent literature 1, it has not been known that therubber composition of the patent literature 1 is applied as the striprubber.

-   [Patent literature 1] Japanese Unexamined Patent Publication No.    2005-239874

SUMMARY OF THE INVENTION

It is the purpose of the present invention to provide a tire having astrip layer between breaker and ply using a rubber composition for astrip layer between breaker and ply capable of improving tensilestrength at break and elongation at break, capable of also lessening thelowering rate of fracture property after thermal aging, and also beingexcellent in separation resistance property.

The present invention relates to a tire having a strip layer betweenbreaker and ply using a rubber composition for a strip layer betweenbreaker and ply comprising (A) 2.0 to 3.9 parts by mass of sulfur, (B)0.5 to 4 parts by mass of a cresol resin, a modified cresol resin,resorcinol or a modified resorcinol condensate, and (C) 0.3 to 3 partsby mass of a partial condensate of hexamethylolmelaminepentamethyletheror a partial condensate of hexamethoxymethylolmelamine, based on 100parts by mass of a diene rubber component, wherein the thickness of thestrip layer between breaker and ply is 0.3 to 3.9 mm.

Further, the content of (D) cobalt is preferably 0.05 to 0.8 parts bymass based on 100 parts by mass of the rubber component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the partial sectional view of the tire showing a structurehaving a strip layer between breaker and ply using the rubbercomposition for a strip layer between breaker and ply of the presentinvention.

FIG. 2 is the partial sectional view of the tire showing a structurehaving a strip layer between breaker and ply using the rubbercomposition for a strip layer between breaker and ply of the presentinvention.

DESCRIPTION OF CODES

-   1 Tread-   2 Sidewall-   3 Carcass ply-   4 Breaker-   5 Inner liner-   6,7 Strip layer between breaker and ply

The strip layer between breaker and ply in the tire of the presentinvention is illustrated below with reference to drawings.

FIG. 1 is a partial sectional view of a tire showing a structure havinga strip layer between breaker and ply using the rubber composition for astrip layer between breaker and ply. Herein, as shown in FIG. 1 that isthe partial sectional view of a tire having a strip layer betweenbreaker and ply, the strip layer 6 between breaker and ply is a rubberlayer provided at the inside of a breaker 4 at the outside of a carcassply 3, in a tire having a tread 1, a sidewall 2, the carcass ply 3provided at the inside of the tread 1 and sidewall 2, the breaker 4provided at the outside of the carcass ply 3 at the inside of the tread1 and an inner liner 5 provided at the inside of the carcass ply 3, andit can improve separation resistance performance without enlarging thethicknesses of the breaker and carcass ply. The maximum value of thewidth of the strip layer 6 between breaker and ply may be the same widthas the breaker 4.

FIG. 2 is a partial sectional view of a tire showing a structure havinga strip layer between breaker and ply using the rubber composition for astrip layer between breaker and ply. In FIG. 2, the width of a striplayer 7 between breaker and ply is a range covering the groove of thetire tread. In FIG. 2, the tread 1, the sidewall 2, the carcass ply 3,the breaker 4 and the inner liner 5 are same as FIG. 1.

DETAILED DESCRIPTION

The tire of the present invention has a strip layer between breaker andply.

The rubber composition for a strip layer between breaker and plyincludes a diene rubber component, (A) sulfur, (B) a cresol resin, amodified cresol resin, resorcinol or a modified resorcinol condensateand (C) the partial condensate of hexamethylolmelaminepentamethyletheror the partial condensate of hexamethoxymethylolmelamine.

The diene rubber component is not specifically limited and includesrubbers such as diene rubbers such as a natural rubber (NR), astyrene-butadiene rubber (SBR) and a butadiene rubber (BR) and butylrubbers such as a butyl rubber, which are generally used in the rubberindustry. Among them, NR is preferably used because the cis structure ofpolyisoprene is nearly 100% and tensile strength is very superior incomparison with other rubber components. One kind or at least two kindsof the fore-mentioned rubber components can be used in combination.

When BR is used in the diene rubber component, a butadiene rubber withhigh cis content (high cis BR) is preferable because it is superior incrack growth property. Herein, the high cis BR means BR in which thecontent of cis 1,4-bond for the butadiene portion of a rubber obtainedis at least 90%.

The high cis BR used in the present invention can use a commerciallyavailable high cis BR and, for example, high cis BR's such as BR130B andBR150B manufactured by Ube Industries can be preferably used.

As (A) sulfur, insoluble sulfur generally used in the rubber industrycan be preferably used.

The content of (A) sulfur is at least 2.0 parts by mass based on thediene rubber component, preferably at least 2.5 parts by mass and morepreferably at least 2.9 parts by mass because hardness (Hs) is improvedand good. Further, the content of sulfur is at most 3.9 parts by massbased on 100 parts by mass of the diene rubber component, preferably atmost 3.7 parts by mass and more preferably 3.5 parts by mass becausetensile strength at break is superior. Further, when insoluble sulfur isused as (A) sulfur, the content of sulfur indicates the content of puresulfur content excluding oil content.

The rubber composition used for a strip layer between breaker and plyincludes (B) a cresol resin, a modified cresol resin, resorcinol or amodified resorcinol condensate.

The resorcinol resin means a compound represented by the formula (1).

The modified resorcinol condensate means a condensate in which aresorcinol condensate is alkylated as in the formula (2). Wherein n isan integer. Examples of the modified resorcinol condensate include thosesuch as SUMIKANOL 620 manufactured by Sumitomo Chemical Co., Ltd.),Penacolite Resin as a resorcinol-formalin reaction product (1319Smanufactured by INDSPEC Chemical Corporation) and RSM (a mixture ofabout 60% by mass and about 40% by mass of stearic acid). Among them,Sumikanol 620 is preferable because aging change and stability caused bymoisture absorption are superior.

The cresol resin means a compound represented by the formula (3).Wherein n is an integer of at least 1.

The cresol resin is solid at normal temperature because its chemicalsoftening point is around 100° C. (92 to 107° C.), but a metacresolresin is most preferable because it is easily dispersed because of beingliquid at rubber kneading and further because reaction initiatingtemperature with the partial condensate ofhexamethylolmelaminepentamethylether (HMMPME) used in the presentinvention is around 130° C. and suitably at most at the temperature oftire vulcanization (145 to 190° C.).

The modified cresol resin includes a resin in which the methyl group ofthe terminal of a cresol resin is modified to a hydroxyl group and aresin in which the portion of repeating units of a cresol resin isalkylated.

The content of (B) a cresol resin, a modified cresol resin, resorcinolor a modified resorcinol condensate is at least 0.5 parts by mass, basedon 100 parts by mass of the diene rubber component, preferably at least0.7 parts by mass and more preferably at least 1.0 part by mass becausetensile strength at break and hardness are superior. Further, thecontent of a resorcinol condensate, a modified resorcinol condensate, acresol resin or a modified cresol resin is at most 4 parts by mass,based on 100 parts by mass of the diene rubber component, preferably atmost 3 parts by mass and more preferably 2 parts by mass because tensilestrength at break and tan δ (heat build-up property) are superior. Thepeak of the tensile strength at break is situated where the content of(B) a cresol resin, a modified cresol resin, resorcinol or a modifiedresorcinol condensate is 1.0 to 2.0 parts by mass.

The rubber composition used for a strip layer between breaker and plyincludes (C) the partial condensate ofhexamethylolmelaminepentamethylether (HMMPME) or the partial condensateof hexamethoxymethylolmelamine (HMMM). The partial condensate of HMMPMEmeans those represented by the formula (4). Further, the partialcondensate of HMMM means those represented by the formula (5).

In the formulae (4) and (5), n is an integer of 1 to 3.

The content of (C) the partial condensate of HMMPME or the partialcondensate of HMMM is at least 0.3 parts by mass, based on 100 parts bymass of the rubber component, preferably at least 0.5 parts by mass andmore preferably at least 0.7 parts by mass because adequate hardness isobtained and tensile strength at break is superior. Further, the contentof (C) the partial condensate of HMMPME or the partial condensate ofHMMM is at most 3 parts by mass, based on 100 parts by mass of therubber component, preferably at most 2.5 parts by mass and morepreferably at most 2.0 parts by mass from the viewpoints of improvinglow heat build-up property and being superior in tensile strength atbreak.

The rubber composition used for a strip layer between breaker and plymay include (D) cobalt salt of organic acid from the viewpoints ofcapable of sharing compounding as breaker topping (for coating steelcord) and capable of improving the long-term adhesion property of a plytopping rubber and a ply cord.

Specific example of (D) the cobalt salt of organic acid includes, forexample, cobalt stearate, cobalt naphthenate and cobalt neodecanate.

The content of (D) the cobalt salt of organic acid is preferably atleast 0.05 parts by mass converted to cobalt, based on 100 parts by massof the rubber component, more preferably at least 0.07 parts by mass andfurther preferably at least 0.09 parts by mass. Further, the content of(D) the cobalt salt of organic acid is preferably at most 0.8 parts bymass converted to cobalt, based on 100 parts by mass of the rubbercomponent, more preferably at most 0.6 parts by mass and furtherpreferably 0.4 parts by mass.

The rubber composition used for a strip layer between breaker and plycan also suitably compound carbon black, a reinforcing agent such assilica, zinc oxide, an antioxidant and a vulcanization accelerator inaddition to the rubber component, (A) sulfur, (B) a cresol resin, amodified cresol resin, a resorcinol condensate or a modified resorcinolcondensate, (C) the partial condensate ofhexamethylolmelaminepentamethylether or the partial condensate ofhexamethoxymethylolmelamine and (D) the cobalt salt of organic acid.

When carbon black is compounded as a reinforcing agent, the content ofcarbon black is preferably at least 40 parts by mass, based on the dienerubber component, more preferably at least 45 parts by mass and furtherpreferably at least 50 parts by mass because it is superior inreinforcing property and hardness. Further, the content of carbon blackis preferably at most 80 parts by mass, based on 100 parts by mass ofthe diene rubber component, more preferably at most 75 parts by mass andfurther preferably at most 70 parts by mass because heat build-upproperty and elongation at break are superior.

The nitrogen adsorption specific surface area (N₂SA) of carbon black ispreferably 60 to 130 m²/g, more preferably 65 to 120 m²/g and furtherpreferably 70 to 110 m²/g. When N₂SA is less than 60 m²/g, reinforcingproperty tends to be low and the growth of separation tends to be fast,and when the N₂SA exceeds 130 m²/g, heat build-up tends to be heightenedand separation tends to grow easily.

When silica is compounded as a reinforcing agent, the content of silicais preferably at least 5 parts by mass, based on 100 parts by mass ofthe diene rubber component, more preferably at least 7 parts by mass andfurther preferably at least 9 parts by mass because elongation at breakis superior. Further, the content of silica is preferably at most 30parts by mass, based on 100 parts by mass of the diene rubber component,more preferably at most 25 parts by mass and further preferably 20 partsby mass because hardness is superior.

The nitrogen adsorption specific surface area (N₂SA) of silica ispreferably 30 to 250 m²/g, more preferably 60 to 210 m²/g and furtherpreferably 100 to 190 m²/g. When N₂SA is less than 30 m²/g, elongationat break tends to be low, and when the N₂SA exceeds 250 m²/g, heatbuild-up tends to be deteriorated and dispersion tends to be difficult(the possibility of deterioration of elongation at break).

The antioxidant includes those such as phenylenediamine and those suchas phenylenediamine are preferably used from the viewpoint ofeffectively preventing the oxidation deterioration of a polymer.

The content of the antioxidant is preferably at least 1 part by mass,based on the rubber component, and more preferably at least 1.5 parts bymass. When the content is less than 1 part by mass, the oxidationdeterioration of a polymer tends to be unable to be suppressed. Further,the content is preferably at most 5 parts by mass and more preferably atmost 4 parts by mass. When the content exceeds 5 parts by mass, heatbuild-up property tends to be deteriorated.

The rubber composition used for a strip layer between breaker and plyincludes further zinc oxide.

Zinc oxide is not specifically limited and zinc oxides such as ZINCOXIDE No. 1 and ZINC OXIDE No. 2 available from Mitsui Mining AndSmelting Company, Limited.

The content of zinc oxide is preferably 5 to 30 parts by mass, based on100 parts by mass of the rubber component, and more preferably 7 to 12parts by mass because deterioration resistance is superior.

Further, the rubber composition for a strip layer between breaker andply of the present invention includes preferablyN,N′-dicyclohexyl-2-benzothiazolylsulfenamide as a vulcanizationaccelerator.

As the vulcanization accelerator, those such asN-tert-butyl-2-benzothiazolylsulfenamide,N-cyclohexyl-2-benzothiazolylsulfenamide and N,N′-diphenylguanidine areadditionally mentioned, butN,N′-dicyclohexyl-2-benzothiazolylsulfenamide is preferable because cordadhesion and reversion property are superior.

The content of N,N′-dicyclohexyl-2-benzothiazolylsulfenamide ispreferably 0.5 to 1.5 parts by mass, based on 100 parts by mass of therubber component, and more preferably 0.7 to 1.3 parts by mass becauseadhesion with steel cord is superior.

The rubber composition used for a strip layer between breaker and ply isproduced by a general method. Namely, the rubber composition for a striplayer between breaker and ply of the present invention can be producedby kneading the rubber components and other compounding agents ifnecessary, with a Banbury mixer, a kneader and an open roll and thencarrying out vulcanization.

The rubber composition for a strip layer between breaker and ply is usedas a strip layer between breaker and ply among tire members because itcan improve separation resistance performance and can particularlyimprove the cord adhesion of adjacent breaker and ply at use for a longtime.

The thickness of the strip layer between breaker and ply is at least 0.3mm, preferably at least 0.4 mm and more preferably at least 0.5 mmbecause the elongation at break of compounding itself is kept. Further,the thickness of the strip layer between breaker and ply is at most 3.9mm, preferably at most 3.0 mm and more preferably at most 2.0 mm becauseheat build-up property is superior.

The tire of the present invention is produced by a usual method usingthe rubber composition for a strip layer between breaker and ply of thepresent invention. Namely, the rubber composition of the presentinvention compounding the compounding agents if necessary is extrudedand processed in matching with the form of the strip layer betweenbreaker and ply of a tire at unvulcanization stage and molded on a tiremolding machine by a usual method; thereby unvulcanized tire is formed.The unvulcanized tire is heated and pressurized in a vulcanizerto-produce usual tires for an automobile, and heavy loading tires for atruck and a bus.

EXAMPLE

The present invention is illustrated based on Examples, but the presentinvention is not limited only to Examples.

Various chemicals used in Examples and Comparative Examples are shownbelow as a whole.

-   Natural rubber (NR): RSS#3-   1,4-High cis BR: BR150B manufactured by Ube Industries Ltd.-   Carbon black: LI (N219) (N₂SA: 105 m²/g) available from MITSUBISHI    CHEMICAL CORPORATION.-   Silica: Ultrasil VN3 (N₂SA: 175 m²/g) available from Degussa    Corporation.-   Zinc oxide: GINREI R available from Toho Zinc Co., Ltd.-   Cobalt stearate: Cobalt Stearate (including 10% of cobalt element)    available from Dainippon Ink And Chemicals, Incorporated.-   Stearic acid: KIRI available from NOF Corporation.-   Antioxidant 6C: NOCRAC 6C available from OUCHISHINKO CHEMICAL    INDUSTRIAL CO., LTD.-   Insoluble sulfur: CRYSTEX HSOT 20 (insoluble sulfur including 80% by    mass of sulfur and 20% by mass of oil) manufactured by Flexsys    Chemicals Sdn Bhd.-   Vulcanization accelerator DCBS: NOCCELER DZ-G manufactured by    OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.-   Modified resorcinol resin: SUMIKANOL 620 manufactured by Sumitomo    Chemical Co., Ltd (chemical formula is shown below).

(Wherein R is an octyl group.)

-   Resorcinol resin: RESORCINOL manufactured by Sumitomo Chemical Co.,    Ltd (chemical formula is shown below).

The resorcinol resin is occasionally described as a resorcinol-formalincondensation resin. For example, Penacolite Resin 1319S manufactured byINDSPEC Chemical Corporation (chemical formula is shown below).

-   Metacresol resin: Sumikanol 610 manufactured by Sumitomo Chemical    Co., Ltd (chemical formula is shown below).

(Wherein n=16 to 17.)

Partial condensate of hexamethylolmelaminepentamethylether (HMMPME):SUMIKANOL 507 manufactured by Sumitomo Chemical Co., Ltd. (It includessilica and 35% by mass of oil. Since its raw material is liquid, it isadsorbed on silica.).

Partial condensate of hexamethoxymethylolmelamine (HMMM): SUMIKANOL 508manufactured by Sumitomo Chemical Co., Ltd. (It includes silica and 35%by mass of oil.)

Examples 1 to 12 and Comparative Example 1 to 11

Various chemicals excluding sulfur and a vulcanization accelerator amongthe compounding contents shown in Tables 1 and 2 were kneaded with aBanbury mixer. Sulfur and a vulcanization accelerator were added to thekneaded product obtained, and the mixture was kneaded with an open rollto obtain unvulcanized rubber compositions. The unvulcanized rubbercompositions were vulcanized at 150° C. for 30 minutes to prepare testpieces and tests shown below were carried out using the test piecesobtained. Further, unvulcanized rubber compositions were molded in theform of the strip layer between breaker and ply of a tire so as to begauge (gauge between BrK/Ply) between the strip layer between breakerand ply shown in Tables 1 and 2, laminated with other tire members toform unvulcanized tires and vulcanized by press under condition of 150°C. for 35 min to produce tires (size: 11R22.5) of Examples 1 to 12 andComparative Examples 1 to 11, and tests shown below were carried out.

<Hardness>

The hardness of the test pieces prepared was measured using a JIS-Ahardness meter.

<Tensile Test (Tensile Strength at Break (TB) and Elongation at Break(EB))>

Tensile test was carried out according to JIS K6251 using a No. 3dumbbell, and tensile strength at break (TB) (MPa) and elongation atbreak (EB) (%) of the test pieces were measured. The tensile strength atbreak and elongation at break of the test pieces after thermal oxidationdeterioration under condition of a temperature of 80° C. for 96 hourswas similarly measured. The larger the value of the tensile strength atbreak and elongation at break are, the more superior the tensilestrength at break and reinforcing property are and the value isindicated as good.

The evaluation results of hardness, tensile strength at break (TB) andelongation at break (EB) are respectively shown in Tables 1 and 2.

<Endurance Test for Reproducing the Separation Between Breaker and Ply>

Endurance test for reproducing the separation between breaker and ply isa test where the separation between breaker and ply is reproduced. Thetires were charged in an oven and deteriorated at 80° C. for 3 weeks,and then, running distance until the generation of spreading treadportion was measured when the tires run on a drum at speed of 80 km/h atthe condition of 140% loading which was the maximum loading (maximuminner pressure condition) of JIS specification. The measurement value ofExample 1 was referred to as 100 and values were respectively displayedby index. The larger the value is, the more superior the durability oftread portion (belt layer) is and the value is indicated as good.

The evaluation results of the drum test for reproducing separationresistance are shown in Tables 1 and 2.

TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 11 12 Compounding amount (parts bymass) NR 100 100 100 100 100 100 75 100 100 100 100 100 1,4-High cis BR— — — — — — 25 — — — — Carbon black N219 65 55 65 65 65 65 55 65 65 6565 65 Silica VN3 — 10 — — — — 10 — — — — — Zinc oxide 10 10 10 10 10 1010 10 10 10 10 10 Cobalt stearate 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 — 1.5 Stearic acid — — — — — — — — — — 1.5 — Antioxidant 6C 1.0 1.01.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Insoluble sulfur 3.75 3.75 3.753.13 4.75 3.75 3.75 3.75 3.75 3.75 3.75 3.75 (including 20% of oil) Puresulfur (3.0) (3.0) (3.0) (2.5) (3.8) (3.0) (3.0) (3.0) (3.0) (3.0) (3.0)(3.0) Vulcanization 1.0 1.0 0.5 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0accelerator DCBS Modified resorcinol 1.5 1.5 2.0 2.0 1.0 1.5 1.5 1.5 1.5— 1.5 — resin Resorsinol resin — — — — — — — — — 1.5 — — Metacresolresin — — — — — — — — — — — 1.5 HMMPME 2.0 2.0 3.0 3.0 1.5 — 2.0 2.0 2.02.0 2.0 2.0 HMMM — — — — — 2.0 — — — — — — Gauge between 1.0 1.0 1.0 1.01.0 1.0 1.0 0.5 2.0 1.0 1.0 1.0 BrK/ply Evaluation result Hardness 74 7576 74 74 74 75 74 74 76 75 75 Tensile strength at 25 26 25 24 24 26 2225 25 24 24 26 break (TB) (MPa) After thermal 22 24 22 23 21 23 20 22 2221 20 24 oxidation deterioration Elongation at break 400 440 380 350 420390 360 400 400 380 390 460 (EB) (%) After thermal 360 380 340 330 340360 290 360 360 320 360 370 oxidation deterioration Endurance test for100 115 95 85 85 100 80 70 125 85 95 105 reproducing the separationbetween breaker and ply

TABLE 2 Comparative Examples 1 2 3 4 5 6 7 8 9 10 11 Compounding amount(parts by mass) NR 100 100 100 100 100 100 100 100 100 100 100 1,4-Highcis BR — — — — — — — — — — — Carbon black N219 65 65 65 65 65 65 55 6565 65 65 Silica VN3 — — — — — — 10 — — — — Zinc oxide 10 10 10 10 10 1010 10 10 10 10 Cobalt stearate 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.51.5 Antioxidant 6C 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Insolublesulfur (including 5.63 1.88 1.88 3.75 3.75 3.75 5.63 1.88 3.75 3.75 5.6320% of oil) Pure sulfur (4.5) (1.5) (1.5) (3.0) (3.0) (3.0) (4.5) (1.5)(3.0) (3.0) (4.5) Vulcanization accelerator 1.0 1.0 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 1.0 DCBS Modified resorcinol resin 1.5 1.5 2.0 5 1.5 0.4 1.54.0 1.5 1.5 1.5 HMMPME 2.0 2.0 3.0 2.0 4 2.0 2.0 3.0 2.0 2.0 2.0 HMMM —— — — — — — — — — — Gauge between BrK/ply 1.0 1.0 1.0 1.0 1.0 1.0 1.01.0 4.0 0 4.0 Evaluation result Hardness 77 68 72 81 79 72 77 74 74 — 77Tensile strength at break 24 21 22 24 25 19 25 21 25 — 24 (TB) (MPa)After thermal 18 19 19 20 21 16 19 19 22 — 18 oxidation deteriorationElongation at break (EB) (%) 420 330 320 330 280 390 440 280 400 — 420After thermal 270 270 280 260 190 320 290 200 360 — 270 oxidationdeterioration Endurance test for 65 70 75 70 50 65 75 70 80 40 45reproducing the separation between breaker and ply

According to the present invention, tensile strength at break andelongation at break can be improved, the lowering rate of fractureproperty after thermal aging can be lessened and separation resistanceproperty is excellent, by using a rubber composition including thespecific amounts of sulfur, a cresol resin, a modified cresol resin,resorcinol or a modified resorcinol condensate and the partialcondensate of hexamethylolmelaminepentamethylether or the partialcondensate of hexamethoxymethylolmelamine in the rubber component, forthe strip layer between breaker and ply.

What is claimed is:
 1. A tire having a strip layer between a breaker anda ply, and using a rubber composition for the strip layer between thebreaker and the ply, the rubber composition comprising: 2.0 to 3.0 partsby mass of sulfur; 0.5 to 4 parts by mass of a cresol resin, a modifiedcresol resin, resorcinol or a modified resorcinol condensate; 0.3 to 3parts by mass of a partial condensate ofhexamethylolmelaminepentamethylether or a partial condensate ofhexamethoxymethylolmelamine, based on 100 parts by mass of a dienerubber component; and 5 to 20 parts by mass of silica having a nitrogenadsorption specific surface area of 100 to 190 m²/g, wherein thethickness of the strip layer between breaker and ply is 0.3 to 3.9 mm,and wherein the breaker in a tire widthwise direction is wider than thestrip layer.
 2. The tire of claim 1, further comprising a cobalt salt oforganic acid, wherein the content of the cobalt is 0.05 to 0.8 parts bymass based on 100 parts by mass of the rubber component.
 3. The tire ofclaim 1, further comprising a sidewall provided at an outside of theply, wherein a widthwise end of the sidewall joins a widthwise end ofthe strip layer.